Systematic pyrolysis of commercial polypropylene for chemical recycling applications

Polypropylene is ubiquitous in plastics manufacturing where waste practices lack a sustainable approach and current efforts to recycle polypropylene diminish its mechanical properties. Chemical recycling, such as building copolymers with enhanced properties, is a promising alternative to traditional recycling. Breaking down and functionalizing polypropylene into oligomers allows for upcycling into other polymers. Here, we establish a robust protocol to oligomerize isotactic polypropylene through pyrolysis. While polypropylene pyrolysis has been previously studied, detailed tests to systematically adjust reaction parameters for short polymer and oligomer product characterization are underexplored. We assess kinetics, composition, rheological and thermo-physical properties of the polymer residue and distillate by adjusting key reaction parameters: temperature, reflux rate, reaction time, and catalysts. This protocol targets a pyrolyzed polymer residue comprising vinylidene end groups, with controlled thermo-physical and rheological properties, that can be further functionalized to incorporate into copolymers. Collectively, these studies aim to investigate the viscoelastic properties of functionalized polypropylene and establish heuristics for the design of a new class of polymers.